Conventional spun yarns are normally made by ring spinning or open-end spinning. While such methods produce good quality yarn, there are certain restrictions and complications associated therewith. For instance open-end spinning systems have rather restrictive limitations as to staple length, rotor speeds, twist directions, wrapper fibers, fibers per cross-sectional area, and fiber bending modulus, stiffness, and other properties. According to the present invention, an apparatus and method are provided which seek to eliminate a number of the restrictions associated with open-end spinning, and in general to provide for the production of spun yarn in a simple, uncomplicated manner. The yarns produced according to the present invention have somewhat different appearance and construction characteristics than conventional spun yarns, but definitely have a spun appearance.
The basic apparatus for practicing the methods of the present invention comprises a hollow shaft with at least a portion of the entire circumference thereof being perforated, and mounted for rotation about an axis coincident with the direction of movement of fibers being spun into yarn. The fibers are fed into a first end of the hollow shaft, and the produced yarn is withdrawn from the second end of the hollow shaft. The shaft is caused to rotate at high speed, and a vacuum is applied to the exterior of the shaft to supply an attractive force to the free ends of the fibers interior of the shaft. A vacuum sucks ambient air through a housing interior to act upon the interior of the shaft, imparting rotation to fibers within the shaft.
Spun-type yarn produced according to the present invention may be produced from a wide variety of types of fibers, such as cotton, polyester, rayon, acrylic, wool, mohair, etc., the spinning process not being as dependent upon bending modulus or stiffness of the composite fibers as is conventional open-end spinning. According to the invention, open-end type spun yarn can be formed with fewer fibers per cross-sectional area, and the yarn will have real twist, either "Z" or "S" direction twist. Restrictions on the end use of open-end type spun yarn according to the invention would not be comparable to conventional open-end spun yarns, but rather would be more comparable to conventional ring spun yarns.
According to one aspect of the method according to the present invention, a spun yarn is produced by the following steps: (a) nipping a sliver or roving so that some of the fibers within the fibers or roving have loose ends; (b) transporting the nipped sliver or roving in a linear direction A at a substantially constant linear speed; (c) feeding a core filament into the sliver or roving, after nipping, so that the core filament passes with the nipped sliver or roving in the direction A; and (d) while transporting the sliver or roving, and core filament, in direction A, rotating loose ends of fibers around the fiber mass, and the core filament, the ends being held substantially linearly stationary during rotation, to produce the desired yarn, with core filament. The core filament yarn preferably comprises a full stretched textured yarn, and preferably it is acted upon by putting it under tension, dragging it over a sharp edge of nonconductive material, and releasing the tension to develop crimp.
According to another aspect of the present invention, a method is provided having the same steps (a) and (b) as set forth above, and including the following additional steps: (c) inserting a filament having controlled overfeed into association with the nipped sliver or roving while moving in direction A, at a point B; and (d) immediately after the point B, rotating loose ends of fibers of the nipped sliver or roving, while the ends are held substantially linearly stationary during rotation, to wrap the fiber ends around other fibers and the filament to produce a spun yarn having loop or Boucle effects.
According to yet another aspect of the present invention, a method is provided having the same steps (a) and (b) as the embodiments described above, and comprising the further steps of: (c) feeding a filament yarn into operative association with the nipped sliver and roving as it moves in the linear direction A, while applying a force substantially in direction A effective to break up to about 20% of the fibers of the filament yarn; and (d) while transporting the sliver or roving in direction A, with free ends and with broken fibers, rotating loose ends of fibers and acting upon broken fibers so that the fiber ends are wrapped around the nipped sliver or roving, and the broken fibers interact with the nipped sliver or roving, to produce a yarn having a spun-like appearance.
According to a still further aspect of the present invention, a method of spinning yarn is provided comprising the following steps: (a) Acting upon a sliver or roving to produce fibers, and so that essentially all of the fibers are fibers having short staple lengths and free ends. (b) Transporting the fibers in a linear direction A at a substantially constant linear speed. And, (c) while transporting the fibers, rotating the loose ends to provide a core formed of approximately 20-40% of the fibers, the core having real twist; and approximately 80-60% of the fibers wrapped about the core to provide surface effects, and simulating the appearance of a fully twisted yarn. A yarn produced according to this procedure does realistically simulate the appearance of a fully twisted yarn.
It is the primary object of the present invention to provide for the simple, effective production of spun yarn. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.